Are you logging into the same account?  It should let you continue.

If you haven't efiled or mailed your return or it rejected you can go back in to finish and change anything you want.  Do not click on Amend!

Click on Add a State to let you back into your return.

From Tax Home (the first screen you see after you sign in), scroll down to Your tax returns & documents. You may have to select Show to open the drop down.

Select 2021, and then select Add a State (you're not actually adding a state, this is just the workaround).

To access your current year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

On the Tax Home web page you should have a screen that states Hi (your first name), let's keep working on your taxes!